The present invention relates to game machines, and more particularly to coin-operated game machines in which players can play a game by inserting coins (including tokens).
As coin-operated game machines, slot machines and poker game machines are well known. In a video-type poker game machine, for example, five cards are displayed on a CRT screen, these cards being changed when a start lever is actuated after an optional number of coins are inserted. The changing of the cards is caused to stop automatically or upon pushing a stop button. A hit, that is, the winning of a prize, is determined based on the combination of five cards that is finally displayed on the CRT screen. The number of coins paid out for a hit depends on not only the rank of the obtained hit card combination but also the number of inserted coins. The number of paid out coins becomes larger, the larger is the number of inserted coins. Ordinarily, the number of delivered coins is multiplied by the number of inserted coins for the same hit card combination.
Recently, coin-operated game machines have been provided with microcomputers, by which the probability of obtaining a hit is so controlled as to maintain a nearly constant pay-out rate; for each game, a random value is sampled from a random number generator for comparison with a prize-winning or probability table in order to determine whether the present game is to be set as a hit game, that is, a prize-winning game, and if so, what kind of hit is to occur, and the microcomputer then executes game processing according to a hit game or lost game processing program. In this way, the probability of obtaining a hit can be kept nearly constant because the number of random values corresponding to hits can be predetermined in relation to the number of all random values to be generated by the random number generator.
In this type of coin-operated game machine, if a sampled random value is found to correspond to a hit as a result of comparison with the hit probability table, a hit flag is generated so as to execute hit game processing which makes it easier to obtain a hit. But a hit does not always result from setting a hit flag. For example, in a game machine with hold buttons as disclosed in U.S. Pat. No. 4,700,948, in which a player can move once more any selected symbols after the first stopping of all symbols when the symbol combination displayed at the time of the first stop does not correspond to a hit combination, if the combination sought by actuating the hold buttons does not match the hit symbol combination decided by the microcomputer, a hit cannot occur. It can also be applied in case of a game machine with stop buttons as disclosed in U.S. Pat. No. 4,573,681 if the actuation of the stop buttons were extremely ill-timed. In such a case, the hit flag is stored for the following games in order to keep the pay-out rate constant, so that the following games continue to be processed according to the hit game program until the corresponding hit is obtained.
Such coin-operated game machines, wherein an unsatisfied hit request is held over for one of the following games, has the problem that if a hit game is obtained when a large number of coins have been inserted while a hit request is carried over from the prior game played with only a small number of inserted coins, the number of coins paid out at that time becomes too large due to its proportionality to the number of inserted coins, so that the pay-out rate exceeds the predetermined rate. For example, if players intentionally repeat the game while inserting only one coin and actuating the hold buttons or stop buttons so as not to obtain a hit, and thereafter insert a larger number of coins choosing a time when a hit flag is considered to be set, a great number of coins would be delivered at high probability. Therefore the pay-out rate cannot be exactly controlled.